Containers

[Carlos Martinez Garcia]

I need to use a container for finding elements, but the key is composed.

I have read about map and hash_map, but I don't see the diferences.

hash_map uses a hash function, but I don't know it hash function is
important in terms of efficiency.

Which is the best container for that?

Thanks in advance

 

[Mark P]

I need to use a container for finding elements, but the key is composed.

What do you mean by "composed"?

I have read about map and hash_map, but I don't see the diferences.

A hash_map uses a hash function to place and locate its elements, a map
uses a comparison function to keep its elements sorted and uses binary
search to place and locate them. Assuming you have a good enough hash
function, inserts, finds, and removals on a hash_map are O(1), whereas
they are O(log N) on a map. However if you need to iterate through the
elements in sorted order, then a map is your only option. Also,
hash_map is currently not standard and therefore not necessarily portable.

hash_map uses a hash function, but I don't know it hash function is
important in terms of efficiency.

Naturally, this depends. It can be.

Which is the best container for that?

For what?

-Mark